Method of making a pressure-sensitive adhesive fastener

ABSTRACT

A pressure-sensitive adhesive fastener having a textured fastening surface so as to have a relatively high shear resistance and a desired peel resistance. The pressure-sensitive adhesive fastener comprises a backing web having bulbous surface aberrations projecting from a first surface of the backing web and a layer of pressure-sensitive adhesive coated over and bonded to at least a portion of the surface of the bulbous surface aberrations of the backing web. The present invention also relates to a fastening system using the pressure-sensitive adhesive fastener of the present invention.

This is a division of application Ser. No. 07/409,206, filed on Sep. 19,1989, now U.S. Pat. No. 4,946,527.

FIELD OF THE INVENTION

The present invention relates to pressure-sensitive adhesive fastenerswhich can be repeatedly fastened and unfastened, and, more particularly,to a pressure-sensitive adhesive fastener having bulbous protuberancesthat permit the fastener to resist shear stress and certain peel forcesencountered during use. The invention also relates to a method of makingthe fasteners and to articles, especially disposable absorbent articles,for which the fasteners are particularly useful.

BACKGROUND OF THE INVENTION

Disposable absorbent articles such as disposable diapers are well-knownarticles of manufacture which are worn by infants anul incontinentpersons. Disposable diapers are worn about the lower torso of the wearerand are intended to absorb and contain urine and other body exudatesthereby preventing these exudates from soiling, wetting, or otherwisecontaminating the articles (e.g., clothing, bedding, etc.) which comeinto contact with the diaper wearer.

When using a disposable diaper, the diaper user fits the diaper on thewearer and fastens it about the wearer's waist by a fastening system tothereby affect a side closure. Fitting the diaper about the wearerusually requires the front and back waist portions of the diaper tooverlap each other. Since proper and sustained fit about the waist andlegs of the wearer is vital for optimal performance in terms ofminimizing leakage of body exudates out of the diaper, a diaperfastening system must be able to provide an effective side closure inwhich the front and back waist portions are maintained in an overlappingconfiguration. As the diaper is worn, forces tend to cause theoverlapping portions to shift position relative to each other. In otherwords, the overlapping portions are subjected to forces which tend tocause the portions to assume a position relative to each other which isdifferent from the position they assume when the diaper is initiallyfitted to the wearer. Unless such shifting is limited, the fit andcontainment characteristics of the diaper are degraded as the diaper isworn. Thus, the fastening system must be designed to securely engage soit does not separate due to the peel forces and shear stress encounteredby the fastening system during use.

As used herein, the term "shear stress" refers to the distributed forcesacting tangentially to the surface of contact of the members of thefastening system. During the wearing of a diaper, shear stress tends tocause the members of the fastening system to shift with respect to eachother. Shear stress is to be distinguished from "peel forces" which acton the members of the fastening system so as to separate and disengagefrom each other. A disposable diaper is typically subjected to peelforces in at least three ways. Peel forces are generated by themovements of the wearer during use as they tend to cause the first andsecond members of the fastening system to pull away from each other, bythe wearer in trying to unfasten the fastening system during wear (thisbeing a special problem for disposable diapers worn by infants becauseinfants should not be able to unfasten and remove the diaper on theirown), and by the user to check the diaper for soiling or to remove thediaper from the wearer. Because the fastening system should be able tobe checked and removed by the user and because the user generated peelforces are much higher than the peel forces generated by the first twomethods, the fastening system is preferably designed to have aresistance to peel forces (peel resistance) with respect to only themovement and wearer generated methods. Therefore, the peel resistanceshould only be great enough to prevent failure of the fastening systemduring the first two methods but low enough to allow the user to checkthe diaper for soiling or to remove the diaper from the wearer withoutundue difficulty or tearing of other members of the diaper.

Therefore, it is desirable to design a fastening system capable ofresisting shear stress and peel forces generated by the wearer buthaving a peel resistance low enough to allow the user to easily removethe diaper or check the diaper for soiling.

Typically, fastening systems have been provided which have adequateshear force resistance to prevent the panels from shifting with respectto each other. However, because the shear forces are so high, the peelresistance of the fastening system is also very high. This is generallythe situation because as the coat weight of the adhesive on the smoothsurface of the backing web of the fastener is increased to improve theshear force resistance of the fastener, the peel force resistance alsorapidly increases. The result is that typical fastening systems may ripthe backsheet of the diaper during the process of unfastening it tocheck if the diaper has been soiled or to adjust its fit, therebyleaving a hole in the backsheet of the diaper and rendering the fastenerunrefastenable and the diaper unuseable, due to the high peel resistanceof the fastener. Thus, it would be advantageous to provide a fasteningsystem having a high enough shear resistance to prevent the panels fromshifting with respect to each other and sufficient peel resistance toprevent failure of the fastening system by the wearer's movements but apeel resistance low enough to allow the user to easily remove the diaperand check for soiling or fit without rendering the fastening systemunrefastenable or the diaper unuseable.

It is, therefore, an object of the present invention to provide a uniquepressure-sensitive adhesive fastener.

It is also an object of the present invention to provide apressure-sensitive adhesive fastener having a textured surface.

It is a further object of the present invention to provide apressure-sensitive adhesive fastener capable of resisting relativelyhigh shear stress while having a desired peel resistance.

It is still a further object of the present invention to provide afastening system utilizing the pressure-sensitive adhesive fastener ofthe present invention.

It is an even further object of the present invention to provide adisposable absorbent article such as a diaper having a fastening systemthat maintains the fit of the diaper at the wearer's waist and legsduring wear and that is able to resist peel forces and shear stressencountered during use while allowing the user to easily check thediaper for soiling or to remove the diaper without rendering thefastening system unrefastenable or the diaper unuseable.

These and other objects of the present invention will be more readilyapparent when considered in reference to the following description andwhen taken in connection with the accompanying drawings.

SUMMARY OF THE INVENTION

According to the present invention, a pressure-sensitive adhesivefastener has a textured fastening surface so as to have a relativelyhigh shear resistance and a desired peel resistance. Thepressure-sensitive adhesive fastener comprises a backing web havingbulbous surface aberrations projecting from a surface of the web and alayer of pressure-sensitive adhesive coated over and bonded to at leasta portion of the bulbous surface aberrations of the backing web.

In addition, the present invention relates to a fastening system usingthe pressure-sensitive adhesive fastener of the present invention. Whilethe fastening system may take many forms, the fastening systempreferably comprises a first member comprising the pressure-sensitiveadhesive fastener and a landing member engageable with thepressure-sensitive adhesive fastener. The landing member has a texturedsurface, preferably a surface that allows nesting of the bulbous surfaceaberrations of the first member with the textured surface of the landingmember, so that the desired properties of the fastener are obtained.

Further, the present invention relates to disposable absorbent articlessuch as a diaper or a sanitary napkin having a fastening systemaccording to the present invention. The diaper fastening system affixesthe overlapping portions of the diaper to each other and maintains themin contact with each other during use. The fastening system preventsseparation of the overlapping waist portions because the fasteningsystem is able to resist the wearer-generated peel forces encounteredduring wear and the shear stress encountered when the diaper is worn.Further, the fastening system allows the user to easily refasten andcheck the diaper for soiling and remove the diaper without rendering thefastening system unrefastenable or the diaper unuseable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cut-away perspective view of a pressure-sensitiveadhesive fastener of the present invention.

FIG. 2 is an enlarged fragmentary sectional view taken along line 2--2of FIG. 1.

FIG. 3 is a perspective view photomicrograph enlarged approximately 175times of a backing web of the pressure-sensitive adhesive fastener ofthe present invention having a 100×100 mesh pattern.

FIG. 3a is a perspective view photomicrograph enlarged approximately90.5 times of a pressure-sensitive adhesive fastener comprising abacking web similar to that shown in FIG. 3.

FIG. 4 is a partially cut-away perspective view of a fastening system ofthe present invention comprising a first member comprising thepressure-sensitive adhesive fastener of the present invention and alanding member comprising the pressure-sensitive adhesive fastener ofthe present invention.

FIG. 5 is a partially cut-away perspective view of a diaper embodyingthe fastening system and the pressure-sensitive adhesive fastener of thepresent invention.

FIG. 6 is an enlarged fragmentary sectional view taken along line 6--6of FIG. 5.

FIG. 7 is a partially cut-away plan view of a sanitary napkin embodyingthe pressure-sensitive adhesive fastener of the present invention.

FIG. 8 is a sectional view taken along line 8--8 of FIG. 7.

FIG. 9 is a side view of an apparatus and method for making thepressure-sensitive adhesive fastener of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

While the present invention will be described in the context ofproviding a fastening system for disposable absorbent articles such asdiapers or sanitary napkins, the present invention is in no way limitedto such applications. The present invention may, in fact, be practicedto great advantage in any situation wherein a pressure-sensitiveadhesive fastener exhibiting the following described characteristics isrequired. It is believed the detailed description contained herein,which relates to a preferred structure and its use as a fastener on adisposable absorbent article, will allow one skilled in the art toreadily adapt the invention to other applications.

A preferred embodiment of a pressure-sensitive adhesive fastener 20having a textured fastening surface 22 according to the presentinvention is illustrated in FIG. 1. The fastener 20 comprises a backingweb 24 having bulbous surface aberrations 26 and a layer ofpressure-sensitive adhesive 28 coated over and bonded to at least aportion of the surface of the bulbous surface aberrations 26.

The backing web 24 generally shown in FIG. 1 has a first surface 30 anda second surface 32, and exhibits a pattern of discrete, bulbous surfaceaberrations 26 projecting from the first surface 30 so as to provide apressure-sensitive adhesive fastener 20 having a textured fasteningsurface 22. Each of the bulbous surface aberrations 26 has a baseportion 34 and an end portion 36. As used herein, the term "bulboussurface aberration" relates to protuberances having an enlarged,generally rounded or pear-shaped, end portion 36 in comparison to thebase portion 34. Thus, the diameter of the bulbous surface aberration 36in the X axis increases in some plane, X₂, in comparison to anotherplane, X₁, as one moves up the vertical Y axis.

The bulbous surface aberrations 26 of the present invention can, thus,have a variety of shapes. The shape of the bulbous surface aberrations26 can have numerous regular shapes such as a mushroom-like shape ornumerous irregular shapes such as an asymmetrical propeller. The endportion 36 of each of the bulbous surface aberrations 26 most preferablycomprises at least one microbubble 38. The microbubbled end portion 36of each bulbous surface aberration 26 comprises a relatively thin,highly flexible, continuous membrane joined about its periphery to therelatively thicker base portion 34 originating in the plane of thebacking web 24.

As shown in FIG. 2, the maximum internal cross-sectional area of thethinned membrane end portion 36 comprising each microbubble 38 (asmeasured in plane X₂ in FIG. 2), is greater than the minimum internalcross-sectional area (as measured in plane X₁ in FIG. 2), of therelatively thicker base portion 34 of the bulbous surface aberration 26from which the microbubble 38 originates. These measurements are made ina pair of parallel planes oriented perpendicular to the amplitude oraxis of the bulbous surface aberration 26 (as represented by "Y" in FIG.2) with the microbubble 38 in its fully expanded condition. Thisproduces a bulbous surface aberration 26 having a mushroom-likeappearance or shape when viewed from a side elevation. A particularlypreferred microbubbled web for use as the backing web 24 of the presentinvention is described in U.S. Pat. No. 4,846,821, entitled"Substantially Fluid-Impervious Microbubbled Polymeric Web ExhibitingLow Levels Of Noise When Subjected To Movement". which issued to JulieW. Lyons, Charles F. Battrell, William R. Ouellette, and John J. Curroon Jul. 11, 1989, and which patent is incorporated herein by reference.

A unique feature of the backing webs 24 of the present invention havinga microbubbled end portion 36 is the thinning of the walls as oneproceeds upward from the base to the side walls to the top of thebulbous surface aberration 26. This apparent wall thinning reductionfrom the base to the top of the structure is approximately 10:1. Whilenot wishing to be bound by theory, it is believed the thinning of thewalls is due primarily to the plastic yielding which takes place in themicrobubbled end portion 36 of the bulbous surface aberration 26relative to the more elastic deformation which takes place in the baseportion 34 of the bulbous surface aberration 26. Once plasticdeformation in the end portion 36 has occurred, there is little, if any,tendency towards elastic recovery, i.e., shrinking of the microbubbledend portion 36 of the bulbous surface aberration 26. By way of contrast,there is relatively less plastic deformation occurring in the baseportion 34 of the bulbous surface aberration 26. Accordingly, once theforces causing deformation of the base portion 34 are removed, the baseportion 34 undergoes at least a degree of elastic recovery while theplastically deformed microbubbled end portion 36 joined thereto doesnot. As a result, the minimum internal cross-sectional area of thethicker base portion 34 of the bulbous surface aberration 26, asmeasured in a plane approximately coinciding with the point at which thebase portion 34 is joined to the microbubbled end portion of thisbulbous surface aberration 26 (e.g., plane X₁ in FIG. 2), is typicallysmaller than the maximum internal cross-sectional area of the fullyexpanded microbubbled end portion 36, as measured in a parallel plane(e.g., plane X₂ in FIG. 2) located along the amplitude or axis of thebulbous surface aberration 26. Thus, the bulbous surface aberrations 26of the present invention normally exhibit a mushroom-likecross-sectional appearance or shape when viewed from a side elevation.

The degree of thinning in the microbubbled end portion 36 of the backingweb 24 of the present invention is sufficient to substantially removethe stiffness from the end portion 36 of the bulbous surface aberration26, effectively converting it to a thin, compliant, easily deformable(.highly flexible) membrane. In the event the web of starting material is opaque, the degree of thinning is normally sufficient to render themicrobubbled end portion 36 of the bulbous surface aberration 26substantially transparent. While not wishing to be bound by theory, itis believed that removing the stiffness from the microbubbled endportion 36 of each bulbous surface aberration 26 provides a multiplicityof hinges or flex points throughout the backing web 24. As a result,backing webs 24 having microbubbled bulbous surface aberrations 26according to the present invention are substantially less stiff thanother backing webs 24. This decreased stiffness is important in order toallow the bulbous surface aberrations 26 of the resultantpressure-sensitive adhesive fastener 20 to comply and conform with thecontacting surface of the landing member to which the fastener isattached thereby providing the desired shear and peel properties of thepressure-sensitive adhesive fastener 20.

Because of the extremely thin membrane-like behavior of the microbubbledend portion 36 of the bulbous surface aberration 26, it may be necessaryto subject the backing web samples to be evaluated to a slight fluidpressure to fully expand the microbubbled end portion 36 of the bulboussurface aberration 26 prior to determining if the aforementionedcross-sectional area relationship is present in any given backing websample. A relatively low pneumatic pressure applied to the secondsurface 32 of the backing web 24 will in most instances suffice.

A particularly preferred method for analyzing the cross-section of thebulbous surface aberration 26 involves casting samples of the backingweb 24 while it is in its fully expanded condition, and thereafterphotographing, on a highly enlarged scale, very thin cross-sectionalslices taken from the casting. This procedure is described in detail inthe above-referenced U.S. Pat. No. 4,846,821 issued to Lyons et al . onJul. 11, 1989. It must, of course, be recognized that it will in someinstances be possible to produce sliced web samples of the presentinvention wherein the microbubbled end portion 36 of a given bulboussurface aberration 26 may not exhibit a mushroom shaped cross-sectionwhen viewed from a particular side elevation. This may, in fact, be dueto where the section is taken through the particular bulbous surfaceaberration 26 rather than a failure of the bulbous surface aberration 26to satisfy the cross-sectional area relationship described earlierherein, i.e., the same bulbous surface aberration 26, if sectioned alonga different axis, may indeed exhibit a mushroom-like cross-section.Therefore, any analysis taken to determine if a mushroom-likecross-section exists in the vast majority of bulbous surface aberrations26 present in any given backing web sample should simultaneously examinea multiplicity of bulbous surface aberrations 26 rather than an isolatedbulbous surface aberration 26.

The number of bulbous surface aberrations per square inch on the backingweb 24 can vary by approximately three orders of magnitude. It should benoted that as the number of bulbous surface aberrations per square inchincreases, the size of the bulbous surface aberrations 26 necessarilydecreases. An example of the size range of the bulbous surfaceaberrations 26 is shown in the following table:

    ______________________________________                                        Textured Film                                                                           # Structures   Structure Structure                                  Pattern   per square inch                                                                              Height    Width                                      ______________________________________                                        100 square                                                                              10,000         ˜7 mil                                                                            ˜8 mil                                60 square                                                                              3,600          ˜10 mil                                                                           ˜11 mil                               20 square                                                                                400          ˜15 mil                                                                           ˜16 mil                               60 Twill 3,600          ˜12 mil                                                                           ˜13 mil                              ______________________________________                                    

A backing web 24 having greater than about 62,500 bulbous surfaceaberrations per square inch (about 2 to about 3 mil height and width)represents the upper limit on the number of bulbous surface aberrationsper square inch (a lower limit upon the size of the aberrations). Atthis relatively large number of structures per square inch and smallsize of each bulbous surface aberration 26, there is an impact on theadhesion properties of the pressure-sensitive adhesive fastener 20. Thebulbous surface aberrations 26 become so small that the coating of evena small amount of pressure-sensitive adhesive onto them would make asmooth continuous fastening surface rather than a textured fasteningsurface 22 as required in the present invention. The result would be aloss of the adhesion benefits of having a pressure-sensitive adhesivefastener 20 having a textured fastening surface 22.

The lower limit on the number of bulbous surface aberrations per squareinch is about 20 bulbous surface aberrations per square inch. Largerbulbous surface aberrations do not have sufficient strength to keep themicrobubble 38 "inflated" during use of the pressure-sensitive adhesivefastener 20. The strength of the microbubbled end portion 36 is relatedto the critical buckling load for each microbubble 38. The criticalbuckling loading is an applied force that causes the microbubble 38 topermanently deform into a new structure. The mathematical theory hasbeen presented by G. Meneges & F. Knipschild for plastics (Mechanics ofCellular Plastics, Ed. N. C. Hilyard, McMillan Publishing, New York(1982)). Generally, the larger the microbubble structure, the less forceis required to buckle the microbubble 38. With all other factors beingnearly equal, such as wall thickness and modulus, then the radius of themicrobubble 38 and the volume fraction of the microbubble 38 become theimportant variables affecting critical buckling load. The volumefraction (ratio of material to cell size of the cell) decreases as themicrobubble size increases. The radius of the microbubble 38 varieslinearly with critical buckling force, whereas the volume fractionvaries by the square power. Thus, a decrease in the volume fractioncorrelates to a squared lowering of the force required to buckle themicrobubble 38. There are several methods to reduce the incident ofbuckling in larger microbubbles, such as reducing the nip roll pressuresencountered during use or lowering the rewind tension. However, at somepoint, the large size of the microbubble 38 will lower the criticalbuckling force such that it is unrealistic to be able to generate anon-buckling bulbous surface aberration 26. A backing web 24 havingabout 20 bulbous surface aberrations per square inch, more practicallyabout 100 bulbous surface aberrations per square inch (diameters andheights of about 20 to about 30 mil) represents the lower limit on thenumber of structures per square inch (upper limit on the size of eachstructure).

The number of bulbous surface aberrations per square inch is preferablyin the range of about 400 to about 10,000 bulbous surface aberrationsper square inch, most preferably from about 1,000 to about 5,000 bulboussurface aberrations per square inch, as measured in an area whichcontains the bulbous surface aberrations 26. It should be noted,however, that the entire first surface 30 of the backing web 24 need notcontain bulbous surface aberrations 26. Bulbous surface aberrations 26may be employed only on those portions of the first surface 30 of thebacking web 24 which are intended to perform a fastening function whileother portions of the first surface 30 need not contain such bulboussurface aberrations 26 so that these portions of the first surface 30may serve additional or other functions in certain predeterminedlocations.

Further, the bulbous surface aberrations 26 employed on the backing webs24 need not all be of the same size or form a regular or repeatingpattern. The pattern, size, and spacing of the bulbous surfaceaberrations 26 may be uniform or non-uniform as desired. For example,the bulbous surface aberrations 26 may be of dissimilar sizes to varythe fastening capability of certain portions of the fastener. In apreferred embodiment of the present invention, the bulbous surfaceaberrations 26 have the same size and are formed on the backing web 24in a regular repeating pattern.

The microbubbled end portion 36 of the present invention is preferably acontinuous membrane (it has a continuous surface) so as to maintain theflexibility of the bulbous surface aberrations 26. The term "continuous"is used herein to mean that the surface or membrane of the end portion36 is uninterrupted by structures formed into the end portion 36. Forexample, the microbubbles 38 may rupture to form a volcanic typestructure (an aperture in the end portion 36). A non-continuous endportion having an aperture would have a very low critical buckling load.Thus, when a layer of pressure-sensitive adhesive is coated onto theapertured end portion, the adhesive would buckle the structure and couldself-adhere and help to set the buckled structure into a non-flexiblestructure. This loss of flexibility in the structure negatively impactson the peel and shear properties of the resultant fastener. Thus, thesurface of the end portion 36 is preferably continuous.

The backing web 24 of the present invention is also preferablysubstantially impervious to adhesive so that adhesive applied to thebacking web 24 does not penetrate through the material forming thebacking web 24 and contact other portions of the backing web 24 ormachinery forming the backing web 24.

In general, it has been found that preferred starting materials to beused as the incoming film for producing the backing webs 24 of thepresent invention are polymeric film materials (polymeric webs).Preferred plastic resin families for use as the backing web 24 arepolyolefins and thermoplastic elastomers. The polymers can be usedsingularly or blended with other polymer resins. Examples of polyolefinsfor use herein as the backing web 24 include linear polyethylene, bothlow density (LLDPE) and medium density (LMDPE); ethylene-vinyl acetatecopolymer (EVA); ethylene-methyl acrylate copolymer (EMAC);ethylene-ethyl acrylate copolymer (EEA); ultralow-density polyethylene(ULDPE); and polypropylene random ethylene copolymers. Examples ofsuitable thermoplastic elastomers include polyester/polyether blockpolymers, polyamide/polyether block polymers; and ionomer metal salts ofethylene/methacrylic acid copolymers. Preferred materials exhibit a lowdegree of molecular orientation, and most preferably exhibit low-yieldand high-elongation characteristics. In addition, the starting filmspreferably strain harden. Exemplary of preferred starting films arematerials such as linear low-density polyethylene, blends of linearlow-density polyethylene and low-density polyethylene, as available fromEthyl VisQueen of Richmond, Va.; linear very-low-density polyethylene asavailable from TUREX, Inc. of Harrisville, R.I.; and block copolymerssuch as polyester-polyether, which are designated as Hytrel, asavailable from E. I. DuPont Nemours & Co. of Wilmington, Del.

The bulbous surface aberrations 26 and thus, generally, the backing web24 should be wettable by pressure-sensitive adhesives. If the surface ofthe backing web 24 is wettable by pressure-sensitive adhesives, then theadhesive will easily spread over the first surface 30 of the backing web24, especially the bulbous surface aberrations 26, such that a uniformor even coating of adhesive is positioned on the bulbous surfaceaberrations 26 and/or the backing web 24. For water-basedpressure-sensitive adhesives, the surface of most polymeric films can becorona treated to improve the wetting out of the adhesive. Also, thecorona treatment improves the bonding of the pressure-sensitive adhesiveto the surface of the backing web 24. This is important because thefastening system needs to fail at the landing member/pressure-sensitiveadhesive interface during use rather than between the interface betweenthe backing web and the pressure-sensitive adhesive. Corona treatment ofpolymeric films to enhance the wettability and surface adhesion ofmaterials is discussed in U.S. Pat. No. 3,703,569 entitled "CoronaTreatment Of Antistat Containing Sheet Of Ethylene or EthyleneCopolymer" which issued to R. I. Wolkowicz on Nov. 21, 1972; U.S. Pat.No. 4,029,876 entitled "Heat-Treated, Corona Treated Polymer Bodies AndA Process For Producing Them" which issued to Theodore R. Beatty et al .on Jun. 14, 1977; U.S. Pat. No. 4,351,784 entitled "Corona Treatment OfPerforated Film" which issued to Paul E. Thomas et al. on Sep. 28, 1982;and U.S. Pat. No. 4,535,020 entitled "Perforated Film" which issued toPaul E. Thomas et al. on Aug. 13, 1985. Each of these patents areincorporated herein by reference.

The backing web 24 of the present invention can be manufactured using anumber of different methods and procedures. Particularly preferredmethods and apparatus for producing microbubbled backing webs 24 of thepresent invention are described in U.S. Pat. No. 4,772,444, entitled"Method And Apparatus For Making Microbubbled And/Or MicroaperturedPolymeric Webs Using Hydraulic Pressure", which issued to John J. Curro,Charles W. Chappell, and James W. Cree, on Sep. 20, 1988, which patentis incorporated herein by reference. An exemplary method for producingthe microbubbled backing webs 24 of the present invention is describedin the above patent and involves the use of a high-pressure liquidstream. A microbubbled backing web 24 of the present invention was madein accordance with a high-pressure stream liquid process using alaminate structure. The starting material comprised a web which is ablend of polyethylenes, designated Ethyl VisQueen No. XP-4337, as isavailable from Ethyl VisQueen of Richmond, Va. The initial thickness ofthe web prior to processing was nominally 1.2 mils (0.0012 in). Theapertured sheet portion of the forming structure was constructed oflaminar layers of thin metal, each having circular holes measuringapproximately 8 mils (0.008 inches) in diameter. The hole pattern wasregularly spaced and exhibited a density of 100 holes per linear inch by100 holes per lineal inch. The overall thickness of the apertured laminasheet portion of the forming structure measured approximately six mils(0.006 in). Immediately beneath the laminar apertured sheet portion ofthe forming structure there was provided a woven wire porous backuplayer or screen comprised of filaments having a diameter ofapproximately 1 mil (0.001 in) arranged in a twilled Dutch weave pattern(there is a degree of filament overlap with this pattern), the screenhaving a filament density of approximately 325 filaments per lineal inchby approximately 2,300 filaments per lineal inch, as available from theFacet Co. of Greensboro, N.C. The laminar apertured sheet portion andthe porous backup layer were bonded to one another by diffusion bonding,as performed by the Facet Co., to form an integral forming cylinderwhich was mechanically supported at its innermost surface without"blinding" the porosity of the innermost screen. The cylindrical formingstructure rotated about a stationary drum having a centrally locatedvacuum chamber.

The web was fed onto the aforementioned rotating forming structure at aspeed of approximately 300 feet per minute and subjected to a highpressure water jet operating at a gauge pressure of approximately 800pounds per square inch and a water flow rate of approximately 3 gallonsper minute per cross-machine direction of web width. The temperature ofthe water in the high pressure water jet was approximately 180° F., asmeasured at the nozzles.

Cooling water at a temperature of approximately 50° F. was applied at arate of approximately 1 gallon per minute per cross-machine directioninch of web width.

A vacuum chamber was maintained at approximately 7.5 inches of Mercuryto provide screen cooling and chamber venting.

The resultant microbubbled backing web 24 exhibited a regularlyrepeating pattern of bulbous surface aberrations 26, each having ahighly thinned, mushroom-shaped membrane coincident with its point ofmaximum amplitude. The density of the bulbous surface aberrations 26corresponded to the density of the apertures in the laminar aperturedsheet portion of the forming structure, i.e., approximately 100 bulboussurface aberrations per lineal inch by approximately 100 bulbous surfaceaberrations per lineal inch. The overall caliper of the resultantbacking web 24 was approximately 6 mils (0.006 in) , as measured under alow load condition of approximately 0.21 pounds/in² (95 grams/in²). Themicrobubbled end portions 36 of the bulbous surface aberrations 26 ofthe opaque web were substantially transparent.

The second surface 32 of the backing web 24 may be laminated to one ormore additional webs to provide increased strength for thepressure-sensitive adhesive fastener 20. The second web may bemanufactured from a wide variety of materials commonly used for backingsof fasteners. The second web preferably comprises a generally flexiblematerial so as to provide higher peel resistance for the fastener. Thebacking web 24 may be laminated to the other webs by any of the severallamination techniques as is known in the art. For example, the backingweb 24 may be laminated by wet, extrusion, dry, thermoplastic andpressure processes.

When the backing web 24 is laminated to another web(s), severaloperating requirements need to be maintained during the laminationprocess so the bulbous surface aberrations 26 are not altered orchanged. The nip roll pressures of the equipment should be maintainedbelow the critical buckling load of the particular bulbous surfaceaberrations 26. If the laminating processes require heating to dry oractivate certain curing agents, then the temperature of the backing web24 must be maintained below the softening point of the material formingthe backing web 24. The laminated bond strength must be greater than thepeel and shear adhesion forces of the resultant fastener so that thebond between the fastener and the landing member fails before the bondbetween the backing web and the laminated second web.

The second component of the pressure-sensitive adhesive fastener 20 ofthe present invention is a layer of adhesive coated over and bonded toat least a portion of the surface of the bulbous surface aberrations 26.Adhesives useful in the present invention are pressure-sensitiveadhesives formulated to adhere to a surface at ambient temperature bybriefly applying light pressure alone. Pressure-sensitive adhesives thatwork in the present invention are categorized into emulsion, solvent,and hot melt pressure-sensitive adhesives.

Emulsion pressure-sensitive adhesives include a wide variety ofpolymeric materials (usually thermoplastic or elastomerics) dispersed ina continuous aqueous phase. The amount of water in the formulationvaries but usually contains around 50% of water by weight. The emulsionpressure-sensitive adhesives may be applied to the backing web 24 by avariety of coating processes. The removal of water by evaporation isusually aided. As the water is being removed, the dispersed particlesbegin to aggregate into a gel-like mass. After continued removal of thewater, the gel-like mass coalesces into a continuous film.

The solvent pressure-sensitive adhesives consist of thermoplastic orelastomeric compositions dissolved in an appropriate aqueous or organicsolvent at levels from 1% to 99% solids. All polymer systems in thisclass are in solutions in the solvent and are not to be confused withemulsions, where the polymer is actually in dispersions. Solventpressure-sensitive adhesives may be applied to the backing web bycoating processes which are very similar to emulsion processes. Theremoval of solvent can be aided by thermal, vacuum, or forced airprocedures. Thus, removal of the solvent from the pressure-sensitiveadhesive leaves a solid film of adhesive.

Hot melt pressure-sensitive adhesives consist of compositions that arecapable of being melted and applied to a substrate in its molten statewhich then cool and solidify relatively quickly. Examples of suitablehot melt adhesives are ethylene-vinyl acetate (EVA) or rubber-based hotmelt pressure-sensitive adhesives. A particularly preferred hot meltpressure-sensitive adhesive is a Kraton based adhesive with tactifiersand other additives such as the material marketed by Findley Adhesives,Inc. of Elm Grove, Wis., under the tradename Findley 990 or H-2085.

Various polymeric raw materials may be used in the formulation of thepressure-sensitive adhesives useful in the present invention. Exemplaryof polymers known in the art which may be used are natural rubber,polyisobutylene. polyvinyl ether, various types of synthetic rubber,ethylene copolymers, vinyl copolymers, and polyurethanes. The preferredpressure-sensitive adhesives for use in the present invention areemulsion pressure-sensitive adhesives. However, solvent-basedpressure-sensitive adhesives or hot melt pressure-sensitive adhesivescan be applied. Most of the above-mentioned pressure-sensitive adhesiveswhich can be used in the present invention are disclosed in the Handbookof Adhesives at pages 535-539 and 726-728, which are herein incorporatedby reference.

The layer of pressure-sensitive adhesive 28 need be coated on only aportion of the surface of the bulbous surface aberrations 26. Typically,at least the surface of the end portion 36 of each of the bulboussurface aberrations 26 is coated with the adhesive. It is desirable thatthe adhesive be coated on at least the surface of the bulbous surfaceaberrations 26 (both the end portion 36 and the base portion 34). Whileit is envisioned that the pressure-sensitive adhesive could be coatedover just the land portions 39 of the first surface 30 of the backingweb (the land portions 39 being the surface between the bulbous surfaceaberrations 36), it has been found that it is preferable to coat atleast a portion of the surface of the bulbous surface aberrations. Dueto the high speed of and coating techniques used in the manufacturingprocesses used to produce the pressure-sensitive adhesive fasteners ofthe present invention, the pressure-sensitive adhesive is typicallycoated over the first surface 30 of the backing web 24 (i.e., all of thesurface of the bulbous surface aberrations 26 and the land portions 39of the first surface 30 are coated). As shown in FIG. 2, it is desirablethat the pressure-sensitive adhesive is uniformly coated over and bondedto the first surface 30 of the backing web 24 to form a continuous thinlayer of adhesive. However, to reduce the amount of adhesive used inmaking the fastener, only a portion, preferably the microbubbled endportion 36, of the backing web 24, only need be coated with adhesive.

In addition, the layer of pressure-sensitive adhesive 28 need not becoated on each bulbous surface aberration 26 or the entire first surface30 of the backing web 24. (i.e., the area coverage of the adhesive mayvary depending upon the circumstances of use of the fastener.) Forexample, certain zones or areas of the backing web 24 may not be coatedwith adhesive since an adhesive property may not be desired in theseparticular zones or areas. (i.e., partial area coverage of adhesive) Thepattern of the area coverage of the adhesive may thus widely varydepending upon the circumstances of the use of the fastener 20.Preferably, adhesive is coated over the entire first surface 30 of thebacking web 24 such that there is complete area coverage of the firstsurface 30 with a layer of adhesive 28.

The coat weight of the pressure-sensitive adhesive on the backing web 24has significant impact on the adhesion properties of the resultantpressure-sensitive adhesive fastener 20. An excess amount ofpressure-sensitive adhesive coated onto the bulbous surface aberrations26 results in a loss of adhesion benefits since the voids between thebulbous surface aberrations 26 could be completely filled withpressure-sensitive adhesive such that a smooth continuous fasteningsurface would be produced. Thus, in order to maintain a texturedfastening surface 22 for the fastener of the present invention, the coatweight of the pressure-sensitive adhesive should be great enough tocover the first surface 30 of the backing web 24 but not so much as tocompletely fill the void spaces between the bulbous surface aberrations26. It has been found that a pressure-sensitive adhesive coat weightbetween about 0.002 g/in² to about 0.08 g/in² is desirable for thefasteners of the present invention. More specifically, for example, fortypical water-based emulsion pressure-sensitive adhesives applied usinga mayer rod applicator, the typical coat weight for a 5 bar mayer rodapplicator is about 0.0201 g/in² ; for a 10 bar mayer rod applicator thetypical coat weight is about 0.0210 g/in² ; and for a 20 bar Mayer rodapplicator the typical coat weight is about 0.0248 g/in². It has alsobeen found that much less hot melt adhesive may be used in order toeffectively form the fastener of the present invention. For example, fora 5 bar Mayer rod applicator, the typical coat weight of hot meltpressure-sensitive adhesive is about 0.0032 g/in² ; for a 10 bar Mayerrod--the typical coat weight is about 0.0041 g/in² ; and for a 20 barmayer rod--the typical coat weight is about 0.0549 g/in².

Whether or not repeated pressure-sensitive adhesive coatings have beenmade onto the backing web 24 also has significant impact on the adhesionproperties of the resultant pressure-sensitive adhesive fastener 20.Repeat coating of the pressure-sensitive adhesive onto the backing web24 introduces a structure factor to the surface of the fastener. Thepressure-sensitive adhesive bridges the gap from the top of one bulboussurface aberration 26 to another. This phenomenon provides an adhesionbenefit of increasing the level of fast grab for the substrate. Forpressure-sensitive adhesive systems, fast grab is defined assufficient/adequate bond security under low load applications. One mustbalance the benefit of the fast grab provided by the bridging of thepressure-sensitive adhesive with the danger that repeat coatings ofadhesive may fill the void between the bulbous surface aberrations 26.Thus, the above-defined coat weights have been found desirable inproviding the maximum benefit for the fasteners of the presentinvention.

Several methods for coating and bonding pressure-sensitive adhesivesonto the backing web 24 may be used to apply the pressure-sensitiveadhesive to the backing web 24. For example, excess coating techniquesmay be applied to coat the pressure-sensitive adhesive onto the backingweb 24. An unmetered or partially metered volume of pressure-sensitiveadhesive is applied onto the backing web 24. A post-coating meteringsystem removes the excess coating via a knife, blade, rod, and/or a dipcoater as are known in the art. Another technique is to pre-meter coatthe pressure-sensitive adhesive onto the backing web 24. A predeterminedvolume of pressure-sensitive adhesive is applied onto the backing web24. Post-metering is not required since the applied volume has beenaccurately controlled via, for example, rotogravure, offset gravure,kiss roll pressure, reverse roll, spray curtain, cast and/or orificecoaters as are known in the art. Further, a hybrid coating technique maybe used to coat the pressure-sensitive adhesive onto the backing web 24.This technique would combine the excess and premetered coatingprincipals. For example, the pressure-sensitive adhesive may be kisscoated via air blade doctoring onto the backing web 24 and post-meteredwith roll pressure with a finishing bar to obtain the same results. Anexcellent review of the details of each of the above techniques can befound in Coating and Laminating Machines, H. B. Weiss, ConvertingTechnology Company, Milwaukee, Wisc. (1977), incorporated herein byreference.

The backing web is made by continuously bringing a flat backing web incontacting relation with a continuous, moving forming member exhibitinga first pattern of apertures substantially corresponding to the bulboussurface aberrations and extending from the outermost of the innermostsurface of the forming member and simultaneously contacting the secondsurface of the flat backing web with a resiliently deformable rollhaving a multiplicity of liquid-filled capillary networks about itsperiphery. During the time the flat backing web is supported on theforming member, a sufficient force is applied between the forming memberand the resiliently deformable roll to at least partially collapse theliquid-filled capillary network. The collapse of the capillary networkcauses the liquid containing therein to permanently deform the backingweb towards the forming member without rupturing the backing web suchthat the backing web acquires a pattern of bulbous surface aberrationssubstantially coinciding with the image of the first pattern ofapertures in the forming member. This is a result of the hydraulicpressure exerted by the liquid contained in the capillary networks.

An exemplary method of making the pressure-sensitive adhesive fastener20 in accordance with the present invention is illustrated in FIG. 9. Asshown in FIG. 9, after the bulbous surface aberrations 26 have beenformed on the backing web 24, the backing web 24 is fed (about 20 toabout 40 feet per minute) from an unwind roll 900 to a corona treatmentapparatus 910 wherein the backing web 24 is corona treated to allow formore uniform dispersion of adhesive over the first surface 30 of thebacking web 24, especially over the bulbous surface aberrations, 26. Thebacking web is then passed over a single roll kiss coater 920 where anunmetered or partially metered amount of water-based emulsionpressure-sensitive adhesive is applied. The coated backing web 24 isthen passed over a Mayer rod 930 for metering the final cast weight ofadhesive onto the backing web. The composite material is then passedinto an infrared dryer 940 (37.5 kilowatt/440 volt) which preferablyoperates at 1/3 power with an air exhaust temperature of 100° F. for aperiod of time of 10 to 30 seconds to bond the adhesive to the backingweb. The resultant pressure-sensitive adhesive fastener 20 is then takenup by a wind-up roll 950.

A coating process objective should be to minimize the deformation of thecoated bulbous surface aberrations 26. Elevated temperatures, excessivemetering pressure or elevated rewind roll tension can and willpermanently deform the coated surface of the bulbous surface aberrations26 on the backing web 24. Thus, certain temperatures, pressures andtensions should be avoided. These may be determined according to theparticular backing web 24 used in the process.

The present invention also relates to a fastening system for securingtwo articles to each other that utilizes the pressure-sensitive adhesivefastener 20 of the present invention. As shown in FIG. 4, the fasteningsystem 40 preferably comprises a first member 42 comprising thepressure-sensitive adhesive fastener 20 as previously described hereinand a landing member 44 engageable with the pressure-sensitive adhesivefastener 20.

The landing member 44 is the body or material in which the first member42, the pressure-sensitive adhesive fastener 20 of the presentinvention, comes into contact during use. (i.e., the adherend). Thebenefits of the shear and peel properties of the pressure-sensitiveadhesive fastener 20 of the present invention is particularly achievedwhen the landing member 44 has a textured contacting surface 46.("Textured" is used herein to mean surfaces that have surfaceprojections.) Without wishing to be bound by any theory, a landingmember 44 having a textured contacting surface 46 is more effectivebecause the bulbous surface aberrations 26 of the pressure-sensitiveadhesive fastener 20 mechanically interfere with the projections on thetextured contacting surface 46 of the landing member 44 to increase theshear force resistance while the peel force resistance is enhancedbecause a greater amount of surface area between the two components isadhesively in contact. Conversely, as the contacting surface 46 of thelanding member 44 becomes flatter or smoother, the shear forceresistance decreases and the peel force is reduced to near zero becausethe bulbous surface aberrations 26 are not interfering with theprojections on the contacting surface 46 of the landing member 44 andless, if almost insignificant, surface area is adhesively in contact.Thus, the texturing of the contacting surface 46 of the landing member44 has a large degree of control on the final properties of thefastening system 40.

The landing member 44 may comprise a large variety of materials havingtextured contacting surfaces 46 including nonwoven webs, polymericfilms, woven webs, cloths with weaving in the surfaces or knitting,skin, a backing web having bulbous 5, surface aberrations 26 of the typehereinbefore described, or another pressure-sensitive adhesive fastenerof the present invention.

To fasten two objects together, the textured fastening surface 22 of thepressure-sensitive adhesive fastener 20 of the present invention iscontacted to the textured contacting surface 46 of the landing member 44and slight pressure is applied to one or both of the members to adherethe two objects together.

Fastening systems of the present invention have been found to beparticularly useful and beneficial when applied to disposable absorbentarticles. As used herein, the term "disposable absorbent article" refersto articles which absorb and contain body exudates and, morespecifically, refers to articles which are placed against or inproximity to the body of the wearer to absorb and contain the variousexudates discharged from the body and which are intended to be discardedafter a single use (i.e., they are not intended to be laundered orotherwise restored or reused). Examples of suitable disposable absorbentarticles include diapers, incontinent briefs and undergarments, sanitarynapkins, bibs, bandages, and the like.

A preferred embodiment of a disposable absorbent article embodying thepresent invention is shown in FIG. 5 as a diaper 50. As used herein, theterm "diaper" refers to a garment generally worn by infants orincontinent persons that is drawn up between the legs and fastened aboutthe waist of the wearer. Examples of the kinds of diapers to which thepresent invention is very readily adapted are shown in U.S. Pat. No.26,151 entitled "Disposable Diaper" which reissued to Robert C. Duncanand Norma L. Baker on Jan. 31, 1967; in U.S. Pat. No. 3,860,003 entitled"Contractable Side Portions For Disposable Diaper" which issued toKenneth B. Buell on Jan. 14, 1975; and in U.S. Pat. No. 4,834,735entitled "High Density Absorbent Members Having Lower Density And LowerBasis Weight Acquisition Zones" which issued to Miguel Alemany andCharles J. Berg on May 30, 1989, which patents are incorporated hereinby reference. It will be apparent from the following description thatthe fastening system illustrated and described herein may be applied tothe body portion of such diapers. On the other hand, it will beunderstood the invention is not limited to any specific diaper structureor configuration.

FIG. 5 is a partially cut-away perspective view of a diaper 50 embodyingthe present invention prior to it being placed on the wearer by thediaper user. As can be seen in FIG. 5, a preferred diaper 50 comprises abody portion 52 and a fastening system 54.

A preferred body portion 52 comprises a liquid pervious topsheet 56, anabsorbent core 58, a liquid impervious backsheet 60, and elasticallycontractible leg cuffs 62, each leg cuff preferably comprising a sideflap 64 and one or more elastic members 66. While the topsheet 56, theabsorbent core 58, the backsheet 60, the side flaps 64, and the elasticmembers 66 may be assembled in a variety of well known configurations, apreferred disposable diaper configuration is shown and describedgenerally in the above-referenced U.S. Pat. No. 3,860,003 which issuedto Kenneth B. Buell on Jan. 14, 1975, and which patent is incorporatedherein by reference. In this preferred diaper configuration, thebacksheet 60 is joined with the topsheet 56; the absorbent core 58 ispositioned between the topsheet 56 and the backsheet 60; the side flap64 extends outwardly from and along each side edge of the absorbent core58; and the elastic member 66 is operatively associated with each sideflap 64.

FIG. 5 shows a preferred embodiment of the body portion 52 in which thetopsheet 56 and the backsheet 60 are coextensive and have length andwidth dimensions generally larger than those of the absorbent core 58.The topsheet 56 is superposed on the backsheet 60 thereby forming theperiphery 68 of the body portion 52, in other words, the outer extent ofthe body portion 52. The periphery 68 comprises longitudinal edges 70and end edges 72.

The body portion 52 has an inside surface 74 and an outside surface 76.In general, the outside surface 76 of the diaper 50 extends from one endedge 72 to the other end edge 72 of the diaper 50 and from onelongitudinal edge 70 to the other longitudinal edge 70 of the diaper 50and is the surface farthest from the wearer during use of the diaper 50.When a backsheet 60 is used, it typically forms the outside surface 76of the body portion 52. The inside surface 74 is that surface of thediaper 50 opposite the outside surface 76 and in the embodiment shown istypically formed by the topsheet 56. In general , the inside surface 74of the diaper 50 is that surface coextensive with the outside surface 76and which is for the greater part in contact with the wearer when thediaper 50 is worn.

The diaper 50 has a first end region 78 and a second end region 80extending from the end edges 72 of the diaper periphery 68 toward thelateral centerline of the diaper 50. Both the first end region 78 andthe second end region 80 extend a distance of about one-half the lengthof the diaper 50 such that the end regions comprise each half of thediaper 50.

Both the first end region 78 and the second end region 80 have panels82. The panels 82 are those portions of the first end region 78 and thesecond end region 80 which overlap when the diaper 50 is fastened aboutthe waist of the wearer. The extent to which the end regions overlap andthus the extent to which the panels 82 are formed, will depend on theoverall dimensions and shape of the diaper 50 and the size of thewearer.

The diaper 50 is provided with a fastening system 54 for forming a sideclosure. Thus, the diaper 50 is fitted to the wearer and the panels 82of the first end region 78 and the second end region 80 are maintainedin an overlapping configuration when the diaper 50 is worn.

In a preferred embodiment of the present invention as shown in FIG. 5,the fastening system 54 comprises a closure member 84 disposed adjacenteach longitudinal edge 70 of the body portion 52 in the first end region78, and a landing member 44 disposed on the outside surface 76 of thebody portion 52 in the second end region 80. As shown in FIG. 5, theclosure member 84 preferably comprises a tape tab 86 and thepressure-sensitive adhesive fastener 20 of the present invention (afirst fastening element 88) while the landing member 44 preferably has atextured contacting surface 46 engageable with the first fasteningelement 88.

Each closure member 84 is intended to provide a fastening means forengaging the landing member 44 so as to provide a secure side closurefor the diaper 50. Thus, the closure member 84 comprises at least thefirst fastening element 88. Each closure member 84 also preferablycomprises a means for positioning the first fastening element 88adjacent the landing member 44 so as to achieve a side closure. Thus,the closure member 84 may comprise any of the well known configurationsand securement means for achieving a side closure on a diaper 50 such asan inner fastening member secured to the inside surface 74 and/or theoutside surface 76 of the body portion 52, tape tabs, or belts. Anexemplary embodiment of an inner fastening member is described in U.S.Pat. No. 4,699,622 entitled "Disposable Diaper Having An Improved SideClosure" issued to John W. Toussant and Margaret H. Hasse on Oct. 13,1987, which patent is incorporated herein by reference. An embodiment ofan incontinent undergarment using a belt suspension system is disclosedin U.S. Pat. No. 4,315,508 entitled "Self-Centering Multiple Use GarmentSuspension System" issued to Bolick on Feb. 16, 1982, incorporatedherein by reference.

As shown in FIG. 5, each closure member 84 most preferably comprises atape tab 86. Any of the well known configurations and constructions of atape tab 86 may be used. A preferred tape tab is a Y-shaped tape tab asdescribed in detail in U.S. Pat. No. 3,848,594 entitled "Tape FasteningSystem For Disposable Diaper" which issued to Kenneth B. Buell on Nov.19, 1974 and which patent is incorporated herein by reference. As shownin FIG. 5, a tape tab 86 is provided on both longitudinal edges 70 ofthe body portion 52, most preferably in the first end region 78.

A particularly preferred tape tab 86 is illustrated in FIG. 6 and has atab fastening surface 90 and a tab backing surface 92. The tab fasteningsurface 90 is that surface of the tape tab 86 designed to engage thelanding member 44 of the present invention. Thus, the tab fasteningsurface 90 of the tape tab 86 will generally correspond to the insidesurface 74 of the body portion 52. The tab backing surface 92 is thatsurface opposite of the tab fastening surface 90 and generallycorresponds to the outside surface 76 of the body portion 52. The tabbacking surface 92 is thus generally exposed during wear of the diaper50.

The preferred tape tab 86 illustrated in FIG. 6 is one which is anchoredto both the inside surface 74 and the outside surface 76 of the bodyportion 52 to create a fixed end 94 (i.e., that attachment of the tapetab 86 to the diaper 50 made during manufacture of the diaper 50). Thetape tab 86 has another element which forms the tab end 96 (i.e., thatjoint made by the person in securing the diaper 50 to the wearer) thatis secured to the fixed end 94 and extends beyond the longitudinal edge70 of the body portion 52 so as to be secured to the landing member 44.Thus, the preferred tape tab 86 of the present invention has at leastthree elements, a first fixed portion 98, a second fixed portion 100,and a connective portion 102. The first fixed portion 98 is that portionof the tape tab 86 which is attached to the inside surface 74 of thebody portion 52. The second fixed portion 100 is that portion of thetape tab 86 which is attached to the outside surface 76 of the bodyportion 52. The first fixed portion 98 and the second fixed portion 100thus form the fixed end 94 of the tape tab 86. The connective portion102 is that portion of the tape tab 86 which is attached to anotherportion of the diaper 50, generally the landing member 44, by the userwhen securing the diaper 50 on the wearer. The connective portion 102thus forms the tab end 96. Additionally, the outer surface 104 of thesecond fixed portion 100 and the outer surface 106 of the connectiveportion 102 form the tab backing surface 92 of the tape tab 86 while theinner surface 108 of the first fixed portion 98 and the inner surface110 of the connective portion 102 form the tab fastening surface 90 ofthe tape tab 86.

The preferred Y-shaped tape tab 86 of the present invention can beconstructed in several ways. The first fixed portion 98, the secondfixed portion 100, and the connective portion 102 can each be separatetapes which meet and are joined adjacent the longitudinal edge 70 of thebody portion 52 in an area of joinder. A more practical structure forthe tape tab 86 is one in which the connective portion 102 and eitherthe first fixed portion 98 or the second fixed portion 100 are a unitarystrip of tape material. If the connective portion 102 is unitary withthe second fixed portion 100 as shown in FIG. 2, then the first fixedportion 98 is a separate element which is attached to the combinedconnective portion and the second fixed portion adjacent to thelongitudinal edge 70 of the body portion 52.

Preferred materials for the tape tabs comprise a tape material such astape code numbers XPF14.43.0, Y-9376, or Y-9030 available from TheMinnesota Mining and Manufacturing Company, of St. Paul, Minn. The tapematerial in the embodiments are preferably a polyethylene film having atab attachment means tailored to bond to the polyethylene positioned onthe tape material. The tab attachment means may comprise any of thoseadhesives which provide an adequate bond with other portions of thediaper 50 and is preferably any of the pressure-sensitive adhesiveswell-known to those of ordinary skill in the art. Preferred tabattachment means is a pressure-sensitive adhesive such as Code NumberXPF1.42.34 available from The Minnesota Mining and ManufacturingCompany, of St. Paul, Minn.

The first fastening element 88 of the closure member 84 forms theclosure between the closure member 84 and the landing member 54. Thus,the first fastening element 88 provides an element or elements thatengage the textured contacting surface 46 of the landing member 44 tomaintain the first end region 78 and the second end region 80 in anoverlapping configuration to provide a secure side closure. The firstfastening element 88 comprises the pressure-sensitive adhesive fastener20 of the present invention.

The first fastening element 88 may be a separate member joined to andassociated with the closure member 84 or a unitary member with theclosure member 84. For example, the first fastening element 88 may be adiscrete patch or strip of the pressure-sensitive adhesive fastener 20of the present invention joined with the body port ion 52 or the tapetab 86 (i.e. , a separate member). Alternatively, the backing web 24 ofthe pressure-sensitive adhesive fastener 20 may be formed from the sameelement as an element of the closure member 84, e.g., the material forthe connective portion of the tape tab 86 may comprise the backing web24, such that the first fastening element 88 is a unitary member.Preferably, the first fastening element 88 is a separate strip ofmaterial joined to the fastening surface 90 of the tape tab 86.

The first fastening element 88 is preferably joined to either the bodyportion 52 or the tape tab 86. As used herein, the term "joined"encompasses configurations whereby the first fastening element 88 isreleasably secured to the diaper 50 so the first fastening element 88may be removed from the diaper 50 or its location during use and wherebythe first fastening element 88 is affixed to the diaper 50 such that thefirst fastening element 88 is securely fastened to the diaper 50. Joinedis also used to denote that the first fastening element 88 may bedirectly joined to the diaper 50 or may be indirectly joined to thediaper 50 such as by releasably securing or affixing the first fasteningelement 88 to an intermediate member which is in turn is releasablysecured or affixed to the diaper 50. Preferably, as shown in FIG. 6, thefirst fastening element 88 is directly affixed to the connective portionof the tape tab 86 by a second tab attachment means 112.

In addition, the first fastening element 88 may be positioned anywhereon the diaper 50. When the closure member 84 comprises an innerfastening member, the first fastening element 88 is preferablypositioned in the panels 82 of the first end region 78 adjacent thelongitudinal edges 70. When the closure member 84 comprises a tape tab86, the first fastening element 88 is preferably positioned either onall of or at least a portion of the fastening surface 90, or preferablyon all of or at least a portion of the connective portion 102. Mostpreferably, the first fastening element 88 is disposed on the connectiveportion 102 on the fastening surface 90 of the tape tab 86.

The landing member 44 of the fastening system 54 provides a means forsecuring itself and the closure member 84 together to provide a secureside closure and to maintain the first end region 78 and the second endregion 80 in an overlapping configuration. The landing member 44 may bedisposed anywhere on the diaper 50 so long as it engages the closuremember 84 so as to provide the side closure. For example, the landingmember 44 may be disposed on the outside surface 76 in the second endregion 80, on the inside surface 74 in the first end region 78, or onany other portion of the diaper 50 which is disposed to engage theclosure member 84. In addition, the landing member 44 may either be adiscrete separate element affixed to an element of the diaper 50 (suchas the topsheet 56 or the backsheet 60) or a unitary piece of materialthat is neither divided nor discontinuous with an element of the diaper50 such as the topsheet 56 or the backsheet 60. While the landing member44 can assume varying sizes and shapes, it preferably comprises one ormore (at least one) separate patches of material secured to the bodyportion 52 to allow for a maximum fit adjustment at the waist of thewearer. The preferred embodiment of the diaper 50 illustrated in FIG. 5has a rectangular-shaped landing member 44 secured to the outsidesurface 76 of the body portion 52 in the panels 82 of the second endregion 80 adjacent each of the longitudinal edges 70.

In the embodiment shown in FIG. 5, the landing member 44 preferablycomprises the same structure as the pressure-sensitive adhesive fastener20 of the present invention so that the bulbous surface aberrations 26on each member of the fastening system nest so as to provide a secureside closure.

In use, the diaper 50 is applied to the wearer by positioning the firstend region 78 under the wearer's back and drawing the remainder of thediaper 50 between the legs of the wearer so the second end region 80 ispositioned across the front of the wearer. The connective portion 102 ofthe tape tabs 86 are then positioned adjacent to the landing member 44positioned on the outside surface 76 of the second end region 80 so thetextured fastening surface 22 of the pressure-sensitive adhesivefastener 20 of the first fastening element 88 which is disposed on thefastening surface 90 of the tape tab 86 will engage the texturedcontacting surface 46 of the landing member 44 to form a side closure.

FIG. 7 shows an alternative embodiment of the present invention whereinthe disposable absorbent article is a sanitary napkin 720 designed toreceive and contain vaginal discharges such as menses. Disposablesanitary napkins are designed to be held adjacent to the human bodythrough the agency of a garment, such as an undergarment or a panty orby a specially designed belt. Examples of the kinds of sanitary napkinsto which the present invention is very readily adapted are shown in U.S.Pat. No. 4,687,478 entitled "Shaped Sanitary Napkin With Flaps" whichissued to Kees J. Van Tilburg on Aug. 18, 1987; U.S. Pat. No. 4,589,876entitled "Sanitary Napkin" which issued to Kees J. Van Tilburg on May20, 1986; U.S. Pat. No. 4,681,578 entitled "Pantiliner With VentilationAreas" which issued to Arthur B. Anderson and Sherry L. Brandt on Jul.21, 1987; and U.S. Pat. No. 4,690,680 entitled "Adhesive AttachmentMeans for Absorbent Articles" which issued to Maureen L. Higgins on Sep.1, 1987. Each of these patents are herein incorporated by reference. Itwill be apparent from the following description that the fasteningsystem illustrated and described herein may be applied to such sanitarynapkins. On the other hand, it will be understood the present inventionis not limited to any specific sanitary napkin structure orconfiguration. FIG. 7 is a plan view of a sanitary napkin 720 embodyingthe present invention prior to it being placed in the undergarment ofthe wearer. As can be shown in FIG. 7, a preferred sanitary napkinconstruction comprises a body portion 722 and a fastening system 724.

A preferred body portion 722 comprises a liquid pervious topsheet 726,an absorbent core 728, and a liquid impervious backsheet 730. While thetopsheet 726, the absorbent core 728, and the backsheet 730 may beassembled in a variety of well-known configurations, a preferredsanitary napkin configuration is shown and described generally in theabove-referenced U.S. Pat. No. 4,687,478 which issued to Kees J. VanTilburg on Aug. 18, 1987, and which patent is incorporated herein byreference, wherein the sanitary napkin 720 has flaps 732 and 732'.

The body portion 722 has an inside surface 734 and an outside surface736. In general, the outside surface 736 of the body portion 722 extendsfrom one end edge 738 to the other end edge 738 of the body portion 722and from one longitudinal edge 740 to the other longitudinal edge 740 ofthe body portion 722 and is the surface farthest from the wearer duringuse of the sanitary napkin 720 and is designed to fit adjacent theundergarment of the wearer. When a backsheet 730 is used, it typicallyforms the outside surface 736 of the body portion 722. The insidesurface 734 is that surface of the body portion 722 opposite the outsidesurface 736 and in the embodiment shown is typically formed by thetopsheet 726. In general, the inside surface 734 of the body portion isthat surface coextensive with the outside surface 736 and which is forthe greater part in contact with the wearer when the sanitary napkin 720is worn.

The sanitary napkin 720 is provided with a fastening system 724 forsecuring the sanitary napkin 720 to the undergarment of the wearer.

In a preferred embodiment of the present invention as shown in FIG. 8,the fastening system 724 comprises an attachment member 742 positionedon the outside surface 736 of the body portion 722 of the sanitarynapkin 720 and a release liner 748 releasably attached to the adhesiveof the attachment member 742. The attachment member 742 comprises afastening element 744 comprising the pressure-sensitive adhesivefastener 20 of the present invention. The fastening element 744 may be adiscrete, separate member secured to the outside surface 736 of the bodyportion 722, or a unitary member than is neither divided nordiscontinuous with an element of the sanitary napkin 720 such as thebacksheet 730. In the preferred embodiment shown in FIG. 8, thebacksheet 730 serves as the backing web 24 of the pressure-sensitiveadhesive fastener 20 such that the fastening element 744 is unitary withthe backsheet 730. The pressure-sensitive adhesive fastener 20 istypically formed by coating the outer surface of the backingweb/backsheet with a layer of pressure-sensitive adhesive 28.

The exact pattern of adhesive on the fastening element 744 may widelyvary and take on a number of configurations such as an array of discreteelements. For example, the fastening element 744 may comprise amultiplicity of discrete elements such as strips, circles, triangles, orany other shapes arranged in either a random or regular pattern whichprovides a zone or zones of adhesion. While the size, arrangement, anddisposition of the fastening element(s) on the outer surface may vary,the fastening element 744 preferably comprises a relatively widerectangular shaped layer of pressure-sensitive adhesive that extendslongitudinally along the body portion 722.

In use, the sanitary napkin 720 is secured on the inside of the crotchportion of an undergarment with the pressure-sensitive adhesive fastenerside of the sanitary napkin 720 toward the crotch portion of theundergarment. Thus, the undergarment serves as the landing member forthe fastening system 724. The release liner 748 is removed from theattachment member 742 and the sanitary napkin 720 is secured in positionby pressing the exposed pressure-sensitive adhesive fastener 20 firmlyagainst the crotch material of the undergarment. The bulbous surfaceaberrations 26 of the pressure-sensitive adhesive fastener 20 willengage certain fibers of the undergarment and be secured thereto by thepressure-sensitive adhesive layer 28 to provide a secure attachment ofthe sanitary napkin 720 within the undergarment.

Since a preferred embodiment of the sanitary napkin 720 of the presentinvention comprises flaps 732 and 732', a flap attachment member 746 isalso provided on one or both of the flaps 732 and 732' to maintain theflaps 732 and 732' in position after the flaps 732 and 732' have beenwrapped around the edge of the crotch portion of the undergarment. Arelease liner 748 is positioned over each of the flap attachment members746 to protect the adhesive until the sanitary napkin 720 is used, therelease liner being removed and the flap being wrapped around the edgeof the crotch portion of the undergarment. The flap attachment members746 each preferably comprise the fastening element 744 previouslydescribed that forms the attachment member 742 of the body portion 722.Thus, the flap attachment members 746 each preferably comprise thepressure-sensitive adhesive fastener 20 of the present invention. Asshown in FIG. 8, the flap attachment members 746 thus each comprise thefastening elements 744 that are unitary with the backsheet 730.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications within the scope of this invention.

What is claimed is:
 1. A method for forming a texturedpressure-sensitive adhesive fastener, said method comprising the stepsof:(a) providing a backing web having a first surface and a secondsurface, the backing web having discrete, bulbous surface aberrationsprojecting from the first surface, at least some of said bulbous surfaceaberrations having an end portion and base portion, wherein said endportion comprises at least one microbubble substantially coinciding withthe point of maximum amplitude of said bulbous surface aberration, andsaid microbubble and said base portion of said bulbous surfaceaberration each have opposed walls separated by an intervening space;(b) coating a pressure-sensitive adhesive layer over at least a portionof the surface of at least some of said bulbous surface aberrations; and(c) bonding said pressure-sensitive adhesive layer to said backing web.2. The method of claim 1 wherein said pressure-sensitive adhesive iscoated over the entire surface of at least some of said bulbous surfaceaberrations.
 3. The method of claim 2 wherein said pressure-sensitiveadhesive layer is additionally coated over said first surface of saidbacking web.
 4. The method of claim 3 wherein said pressure-sensitiveadhesive layer is uniformly coated over said first surface of saidbacking web.
 5. The method of claim 3 wherein the step (b) of coatingadhesive comprises:applying a unmetered or partially metered amount ofpressure-sensitive adhesive into said backing web, and removing anyexcess adhesive so as to meter the final coat weight of adhesive on saidbacking web.
 6. The method of claim 3 wherein the step (b) of coatingadhesive comprises applying a predetermined volume of adhesive onto saidbacking web.
 7. A method for forming a textured pressure-sensitiveadhesive fastener, said method comprising the steps of:(a) providing abacking web of polymeric material, said backing web having a firstsurface and a second surface;continuously brining the backing web incontacting relation with a continuous, moving forming member exhibitinga pattern of bulbous apertures extending from the outermost to theinnermost surface of said forming member; contacting the second surfaceof said backing web with a resiliently deformable roll having amultiplicity of liquid-filled capillary networks about its peripherywhile said backing web is supported on said forming member; and applyingsufficient force between said forming member and said resilientlydeformable roll to at least partially collapse said liquid-filledcapillary network on said resiliently deformable roll, thereby causingthe liquid contained therein to permanently deform said backing webtowards said forming member without rupturing said backing web such thatsaid backing web acquires a pattern of bulbous surface aberrationssubstantially coinciding with the image of the pattern of apertures insaid forming member due to the hydraulic pressure exerted by the liquidcontained in said capillary networks, so that at least some of saidbulbous surface aberrations have an end portion and base portion,wherein said end portion comprises at least one microbubblesubstantially coinciding with the point of maximum amplitude of saidbulbous surface aberration, and said microbubble and said base portionof said bulbous surface aberration each have opposed walls separated byan intervening space; (b) coating a pressure-sensitive adhesive layerover at least a portion of the surface of at least some of said bulboussurface aberrations of said backing web; and (c) bonding saidpressure-sensitive adhesive layer to said backing web.
 8. The method ofclaim 7 additionally comprising the step of corona-treating said backingweb of polymeric material prior to applying the pressure-sensitiveadhesive layer over said backing web so as to make said backing webwettable by the pressure-sensitive adhesive.
 9. A method for forming atextured pressure-sensitive adhesive fastener, said method comprisingthe steps of:(a) providing a backing web having a first surface and asecond surface, the backing web having discrete, bulbous surfaceaberrations projecting from the first surface, at least some of saidbulbous surface aberrations having an end portion and base portion,wherein said end portion comprises at least one microbubblesubstantially coinciding with the point of maximum amplitude of saidbulbous surface aberration, and said microbubble and said base portionof said bulbous surface aberration each have opposed walls separated byan intervening space, said microbubble comprising a flexible membranejoined about its periphery to said base portion, said walls of saidmicrobubble thinner than the walls of said base portion of said bulboussurface aberration; (b) coating a pressure-sensitive adhesive layer overat least a portion of the surface of at least some of said bulboussurface aberrations; and (c) bonding said pressure-sensitive adhesivelayer to said backing web.